Disseminator including a rotatable metering wheel with fluid ejector means



J. M. BEEBE DISSEMINATOR INCLUDING A ROTATABLE METERING May 23, 1967 WHEEL WITH FLUID EJECTOR MEANS 2 Sheets-Sheet 1 Filed June 28, 1966 Fig.2

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J. M. BEEBE 3,321,109 DISSEMINATOR INCLUDING A ROTATABLE METERING May 23, 1967 WHEEL WITH FLUID EJECTOR MEANS Filed June 28, 1966 2 Sheets-Sheet 2 Fig.4

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United States Patent DISSEMINATDR INCLUDING A ROTATABLE METERING WHEEL WITH FLUID EJECTOR MEANS James M. Beebe, Frederick, Md., assignor to the United States of America as represented by the Secretary of the Army Filed June 28, 1966, Ser. No. 562,432 Claims. (Cl. 22---194) The invention described herein may be manufactured and used by or for the Government of the United States of America for governmental purposes without the payment to me of any royalty thereon.

This invention relates in general to a disseminator and more particularly to a disseminator utilized in the generation of dynamic dry aerosols of small particle size.

When trying to reproduce field conditions in the laboratory, it is often necessary to assay a non aging cloud and/ or expose animals to the same cloud. A variety of tubular or tunnel-like, i.e., dynamic tubes, may be used for this purpose, e.g., the Henderson and Plummer tube. The aeroasol cloud may be passed continuously through the dynamic tubes at a fixed speed and concentration, thereby resulting in a reproducible cloud concentration of uniform density at a given distance from the aerosol generator. The dispensing of a reproducible cloud concentration of uniform density is readily accomplished utilizing a liquid aerosol generator. However, heretofore there have been no satisfactory methods for the continuous generation of an aerosol cloud from a dry-fill generator at a fixed speed and concentration to obtain a reproducible cloud of uniform density. In the prior art, dry preparations have always been, disseminated in static chambers. The results obtained have not been satisfactory in that the cloud ages with time. Therefore, any repetitive animals exposures tests conducted in said chamber are not comparable in that the exposure conditions therein were not substantially identical.

Most of the prior art dry dust or powder disseminators operate by one of three methods:

(a) Erosion of a column of the dry material by a jet of air,

(b) Creation of a primary aerosol by air or mechanical stirring, and bleeding off the smaller airborne particles that remain suspended, or

(c) Shaving or scraping a solidly compacted cylinder or mass of dry material and suspending the scraped particles in air by a jet or stream of air. However, all of the above mentioned methods have drawbacks. The erosion of a column of the dry material by a jet of air tends to produce an uneven flow of dry particles except at very high rates of feed. The creation of a primary aerosol by air or mechanical stirring, and bleeding off the smaller air-borne particles that remain suspended, is highly selective. The aerosols produced thereby are not representative of the entire dry mass, but consists mainly of the smaller particles. The method of shaving or scraping :a solidly compacted cylinder or mass of the dry material, and suspending the scraped particles in air produces a physical change in the resultant aerosol particles by the compaction and scraping. Thus, the resultant aerosol particles are not representative of the original dry material.

The present device overcomes the above mentioned criticisms. The device comprises a magazine into which the sample is loosely packed. The sample is pushed from the magazine by means of a screw driven piston onto a groved, serrated, knurled, or otherwise roughened rim of a metering wheel. The metering wheel may be rotated at any desirable speed from one to ten r.p.m. Two to three r.p.m. have been found satisfactory for most work. The serrated, grooved, knurled, or roughened surface of ice the rim of the metering wheel carries small amounts of the sample past an air jet, which blows the dry powder secreted in the roughened rim of the metering wheel into an animal exposure tube or other aerosol container. The present apparatus generates a continuous aerosol of uniform density. In addition, the particles remain unchanged in shape, conformation and viability in comparison with the original product. Furthermore, the present apparatus may be adjusted so that the rate of dissemination of the aerosol may be changed without interfering with the uniformity of the discharge. The utilization of the present apparatus has resulted in the obtainment of extremely low rates of discharge of materials, e.g., 2.5 milligrams per minute with less than 0.2 log variation, over periods of up to one hour. With the utilization of the present apparatus, it is possible to obtain replicate doses with any number of experimental animals. This is necessary if one expects to obtain valid experimental results. Otherwise the data obtained is of little value.

It is an object of the invention to provide and disclose a dry-fill disseminator capable of generating aerosols.

Another object of the invention is to provide and disclose a dry-fill disseminator capable of continuously generating aerosols at a uniform rate.

Another object of the invention is to provide and disclose a dry-fill disseminator capable of generating aerosols at an extremely low rate.

Another object of the invention is to provide and disclose a dry-fill disseminator, capable of generating aerosols, wherein the original particle size range remains unchanged.

Another object of the invention is to provide and disclose a dry-fill disseminator capable of generating aerosols comprising viable bacteria wherein the viability thereof is not vitiated.

Other objects and a fuller understanding of the invention may be had by referring to the following description and claims, taken in conjunction with the accompanying drawing, in which:

FIG. 1 shows a sectional side view of the housing of the apparatus.

FIG. 2 shows a top view of the apparatus.

FIG. 3 shows a sectional side view of the apparatus taken through section 10-10 of FIG. 2.

FIG. 4 shows a top sectional view of the apparatus.

FIG. 5 shows an exploded side view of the spur gears.

FIG. 6 shows an exploded sectional view of the spur gear housing and removable cap assembly.

FIG. 7 shows a graphic representation of the concentration of viable cell continuously dispersed per liter of cloud over a period of time.

Referring now to the drawings, the instant device comprises rectangular housing 13 constructed of any suitable material, e.g., metal or plastic. Housing 13 comprises top portion 14, bottom 16, and sides 18 and 20. Top port-ion 14 contains reduced sections 22 and 24. Integral cylindrical housing 37 comprising an internally threaded section 39 extends outwardly at an angle of around 45 from the surface of reduced section 24. Bottom section 16 is attached to base support 11 and by any suitable means, e.g., bolts. Housing 13 contains upright cylindrical hollow section 28 at approximately the center position thereof. Passageway 30 extends from cylindrical hollow section 28 and unites with internally threaded section 39 of integral cylindrical housing 37. Positioned within housing 13 at approximately the center position thereof is rotatably mounted metering wheel 15 comprising a cylindrical metal object having a serrated, grooved, knurled or otherwise roughened rim. The wheel is mounted on main shaft 25. The housing is machined to accept the metering wheel with the minimal tolerances that will still allow it to turn within the housing. Main shaft 25 extends through bore 21 of housing 13 and is mounted on Teflon bearing 26 as shown in FIG. 4. Shaft 25 is connected to any conventional external power source 61, e.g., a one-one-hundredth horsepower speed reducer electric motor, by socket 63 which is secured by set-screws 65, as shown in FIG. 2. Bevel gear 27 is positioned circumferentially on main shaft 25 at a position near side 18 of the housing. A second bevel gear 31, which is identical to bevel gear 27, is positioned immediately adjacent thereto so that the working surfaces of the toothed wheels of the bevel gears are inclined to intersecting axis. Bevel gear 31 is attached to one end of piston drive shaft 29, which comprises a cylindrical metal shaft having a smooth and a threaded end 33 as shown in FIG. 2. Bevel gears 27 and 31 are secured to shafts 25 and 29 by set-screws 47 and 49, respectively. Piston drive shaft 29 is positioned in a direction transverse to main shaft 25 and secured by U shaped support 59, as shown in FIG. 2. U shaped support 59 comprises a pair of bores, not shown, near the open section thereof of a size suflicient to receive and support piston drive shaft 29. The closed section of U shaped support 59 is attached to housing 13 of the apparatus by means. of support screws 67. To threaded end 33 of piston drive shaft 29 is attached spur gear '32, which comprises a threaded bore through the center thereof, suitably contoured to be compatible with the threaded end of piston drive shaft 29. Spur gear 32 is secured to piston drive shaft 29 by means of nut 53, which comprises a hexagonal nut chamfered at one end. In addition, spur gear 32 externally contacts spur gear 34, which comprises a circumference substantially larger than gear 32. The working surfaces of the pair of spur gears are inclined to parallel axis. The rotation of spur gear 32, in a counter clockwise direction motivates spur gear 34 in a clockwise direction; The vertical motion of spur gear 34 is limited by the partial encompassment thereof by spur gear cylindrical housing 55 which comprises an integnal sleeve section 68 extending downwardly therefrom. Integral sleeve section terminates at flared section 69 as shown in FIG. 6. Flared section 69 is supported on cylindrical integral housing 37 and secured by removable cap 57, as shown in FIG. 3. Spur gear 34 has a threaded opening in the center thereof of a size sufiicient to receive piston drive screw 36, which comprises a partially externally threaded elongated cylindrical metal rod. The externally threaded section of piston drive screw 36 is compatible with internal threads 39 of integral cylindrical housing '37. The extreme end of piston drive screw 36 is keyed into magazine cap 23, which comprises a short solid cylindrical object constructed of any suitable material, e.g., Teflon, and suitably contoured so as to be compatible with passageway 30. Piston'drive screw 36 and magazine cap 23, which is attached to the end thereof partially occupy the area within passageway 30. The unoccupied area of passageway 30 is utilized as a magazine to hold the material to be evaluated. The amount of area of passageway 30 which may be utilized as a magazine to hold the sample of dried material, may be varied by adjusting screw 36 attached to spur gear 34 so as to minimize or maximize the initial protrusion of piston drive screw 36 and magazine cap 23 attached thereto into the passageway.

Any inert gas, e.g., air or nitrogen, may be utilized in the present apparatus, provided that it does not react unfavorable with the experiment under consideration. The gas. is stored in tank 46 under pressure and conducted through orifice 17 to the interior of housing 13 by means of tubing '38. The tubing may be constructed of any suitable material, e.g., copper, plastic or metal. Orifice 17 extends through side 18 of the housing and is positioned near the top section of the disseminator on a plane substantially equal with the rim of metering wheel 15. The section of tubing 38 immediately adjacent to orifice 17 comprises a flared end. Said section of tubing is secured to side 18 of the housing 13 by means of externally threaded nut which comprises a passageway therethrough of a size suflicient to receive tubing 38. The gas is emitted from tank 46 by means of feed valve 44. The flow of the gas is further regulated by means of pressure regulator 42, comprising a standard pneumatic pressure regulator pre-set at the desired pressure, which is positioned on tubing 38. Exhaust 41 is positioned directly opposite orifice 17 and provides for the passageway of the aerosol through side 20 of housing 13 to aerosol chamber 45.

Illustrative, but without limitations, a disseminator within the scope of this invention has the following size characteristics: an orifice ,6 in diameter; an exhaust A" in diameter; a magazine A in diameter, and 1" in length; a metering Wheel 2" in diameter by A1 in width.

The manner of operation will now be described. Piston drive screw 36 is removed by the unscrewing thereof from cylindrical integral housing 37 and spur gear 34. The desired amount of material 43 to be evaluated, e.g., 1.5 grams dry Serratia marcescens, is placed in the magazine. Piston drive screw 36 is replaced as shown in FIG. 4. The external power driving the main shaft is activated and the metering wheel is adjusted to operate at a speed of about 2 to 10 rpm. Feed valve 44 is opened and the rate of air flow through orifice 17 is adjusted to about 10 to 20 liters per minute by means of pressure regulator 42. The rotary clockwise motion of main shaft 25 is transmitted to spur gear 32 by means of bevel gears 27 and 31 and piston drive shaft 29. The counter clockwise rotation of spur gear 32 motivates externally contacted spur gear 34 in a clockwise rotation. The clockwise rotation of spur gear 34 moves piston drive screw 36 and magazine cap 23 attached thereto. in a downward direction thereby compressing the magazine chamber, and moving sample 43 upon the rim of metering wheel 15. Small amounts of the dry charge from magazine are continuously picked up on the serrated or grooved rim of metering wheel 15 and moved into position for dissemination by a jet or gas from air nozzle 17.

The device was operated for a period of 21 minutes utilizing 1.5 grams of dry viable Serratia marcescens. The metering wheel was rotated at a speed of 2.5 rpm. The gas flow was maintained at 25 pounds of pressure as indicated on regulator 42. A uniform cloud comprising a viable cell concentration of approximately 26x10 per liter of cloud was maintained as shown graphically in FIG. 7.

While the basic function of the disseminator as designed is to generate aerosols of dried, ground bacterial cultures with a particle range size of approximately 1 to 10 microns in diameter in order to study the infectivity of such aerosols and the effects of various atmospheric stresses on the stability of dry, air-borne bacteria, the present apparatus might be utilized to distribute thin layers of finely ground chemicals on prepared surfaces,

to air mix chemicals during the course of laboratory or industrial reactions, apply growth factors to green plants or to administer medication to large numbers of animals via the respiratory route.

Although I have described my invention with a certain degree of particularity, it is understood that the present disclosure has been made only by way of example and that numerous changes in the detail of construction and the combination and arrangement of parts may be resorted to without departing from the spirit and the scope of the invention as hereinafter claimed.

I claim:

1. An aerosol producing apparatus comprising a housing having a cylindrical hollow section and a top section, a partially threaded passageway protruding from the surface of the top section and communicating with cylindrical hollow section, a main shaft extending through the housing, means engaging the shaft, a metering wheel rotatably mounted in said cylindrical hollow section and fixed on the main shaft, gas intake means positioned near the top portion of the housing and adjacent to the rim of the metering wheel, exhaust means positioned directly opposite the gas intake means, a bevel gear positioned circumferentially on the main shaft, a second bevel gear positioned immediately adjacent thereto so that the working surfaces of the toothed wheel of the bevel gears are inclined to intersecting axis, the second bevel gear being fixed to one end of a piston drive shaft, which is positioned in a direction transverse to the main shaft, a spur gear fixed to other end of a piston drive shaft, said spur gear externally contacting a second spur gear, the working surfaces of the pair of spur gears being inclined to parallel axis, said second spur gear adapted to receive the threaded portion of an elongated screw at the center position thereof, the threaded section of said elongated screw being compatible with the partially threaded passageway of the housing, a cylindrical cap fixed to the end of the elongated screw protruding into the threaded passageway.

2 An apparatus in accordance with claim 1 wherein the metering wheel comprises a grooved rim.

3. An apparatus in accordance with claim 1 wherein the metering wheel comprises a serrated rim.

41. An apparatus in accordance with claim 1 wherein on the engagement of the main shaft, the elongated threaded screw and cylindrical solid cap attached thereto are projected further into the partially threaded passageway.

S. An apparatus in accordance with claim 1 wherein concurrently on the engagement of the main shaft, gas is received through the gas intake means and expelled through the exhaust means.

References Cited by the Examiner UNITED STATES PATENTS 2,064,742 12/ 1936 Goldsmith 222-26O X 2,152,632 4/1939 Cassiere 222*194 X 2,907,499 10/1959 Agronin 222-494 X 2,914,223 11/1959 Richter 222194 3,201,001 8/1965 Roberts et a1. 222-194 WALTER SOBIN, Primary Examiner. 

1. AN AEROSOL PRODUCING APPARATUS COMPRISING A HOUSING HAVING A CYLINDRICAL HOLLOW SECTION AND A TOP SECTION, A PARTIALLY THREADED PASSAGEWAY PROTRUDING FROM THE SURFACE OF THE TOP SECTION AND COMMUNICATING WITH CYLINDRICAL HOLLOW SECTION, A MAIN SHAFT EXTENDING THROUGH THE HOUSING, MEANS ENGAGING THE SHAFT, A METERING WHEEL ROTATABLY MOUNTED IN SAID CYLINDRICAL HOLLOW SECTION AND FIXED ON THE MAIN SHAFT, GAS INTAKE MEANS POSITIONED NEAR THE TOP PORTION OF THE HOUSING AND ADJACENT TO THE RIM OF THE METERING WHEEL, EXHAUST MEANS POSITIONED DIRECTLY OPPOSITE THE GAS INTAKE MEANS, A BEVEL GEAR POSITIONED CIRCUMFERENTIALLY ON THE MAIN SHAFT, A SECOND BEVEL GEAR POSITIONED IMMEDIATELY ADJACENT THERETO SO THAT THE WORKING SURFACES OF THE TOOTHED WHEEL OF THE BEVEL GEARS ARE INCLINED TO INTERSECTING AXIS, THE SECOND BEVEL GEAR BEING FIXED TO ONE END OF A PISTON DRIVE SHAFT, WHICH IS POSITIONED IN A DIRECTION TRANSVERSE TO THE MAIN SHAFT, A SPUR GEAR FIXED TO OTHER END OF A PISTON DRIVE SHAFT, SAID SPUR GEAR EXTERNALLY CONTACTING A SECOND SPUR GEAR, THE WORKING SURFACES OF THE PAIR OF SPUR GEARS BEING INCLINED TO PARALLEL AXIS, SAID SECOND SPUR GEAR ADAPTED TO RECEIVE THE THREADED PORTION OF AN ELONGATED SCREW AT THE CENTER POSITION THEREOF, THE THREADED SECTION OF SAID ELONGATED SCREW BEING COMPATIBLE WITH THE PARTIALLY THREADED PASSAGEWAY OF THE HOUSING, A CYLINDRICAL CAP FIXED TO THE END OF THE ELONGATED SCREW PROTRUDING INTO THE THREADED PASSAGEWAY. 